The stereotype of the evil, powerful stepmother is just a caricature. But is it possible that we invented this archetype even though stepmothers are arguably the most vulnerable and disempowered members of any blended family? Psychologist Wednesday Martin thinks so.

Citing research that stepmothers suffer from depression at higher rates than both mothers and stepfathers, and the fact that parenting advice for stepmothers is often woefully biased, Martin writes, "the woman with younger stepchildren finds herself in a position of having no say about parenting practices in her own home. The stepmother with older or even adult stepchildren is not necessarily exempt from this problem. Many women told me they had endured snippy remarks and barely veiled hostility from their adult stepchildren." Stepmothers, because they are so eager to be accepted into the family unit, are vulnerable to manipulation. This doesn't sound like a very good deal.

There are all kinds of psychological reasons why this might be so, and Martin points to them: fathers feel guilt for subjecting the kids to the disruption of divorce. Children may project their feelings of upset and loss onto the new woman they, consciously or not, consider at fault. Stepmothers are left to tolerate intentional slights because conventional wisdom encourages them to refer parenting decisions — especially regarding discipline — to the children's "real" parent.

But there are also plenty of cultural reasons for these lamentable family dynamics that came to my mind. for one thing, it's possible that stepmothers are made to feel like "interlopers" for violating that most sacred cultural bond: that between mother and child. Part and parcel with our culture's fetishization of squeaky-clean motherhood is its demonization of anything, or anyone, that gets in motherhood's way. To a lot of women, there may seem something fundamentally unfair about another woman raising their kids. (Look at the outcry that ensued when Gisele Bundchendared tell Vanity Fair that she loved Bridget Moynahan's baby son, Jack, "the same way as if he were mine.") The abuse — whether it's the cute kid in the movie heckling the lady daddy's dating, or something altogether more serious — becomes a kind of righteous payback.

And of course, throughout history, there are many examples of women's power being limited by disinformation and counterfactual stereotypes; think of how the ideal body, as presented by advertising and the fashion industry, has shrunk during the 20th Century, as real women everywhere have made great strides toward equal treatment. It's obvious that the "evil stepmother" never really existed — but it is worth asking why we had to make her up.